Drilling small holes in hardend steel

some is tempered after hardening.

‘Almost all’ would be right. There are other factors.

Drilling a hard material needs a drill harder than the material being drilled.

In the 18th century, not much choice - either the very best carbon steel they could get find and lots of patience and resharpening, or maybe carborundum or diamond. The usual method was to dodge the problem by drilling any holes needed when the steel was still soft. Hardened steel is usually worked by grinding, not by cutting.

Softening spring steel, drilling, and re-hardening is an option but making springs is skilled work. I'd want plenty of successful practice behind me before risking an antique clock, or at least an alternative if I ruined the original part. (An old time clockmaker would keep a few apprentices busy making parts. If anything broke, they'd be beaten soundly and told to do it again. Cost a fortune, which is why later clockmakers increasingly used parts bought in from specialists.)

Today we have more drills suitable for hard drilling, not cheap though! Whatever type is used, lots of pressure and cutting oil are needed. TiN coated HSS or Cobalt drills stand a chance but no tears if a few get destroyed in the process. Solid tungsten drills are perhaps the most affordable approach, but hard means brittle: thus any operator error means an expensive breakage. (A Karnasch 4mm K-Drill Solid Carbide Drill for Hardened Steels is nearly £70 from Cutwel.) Never researched the cost of really high-end drills like Boron Nitride, I guess they're even more pricey.

Spark erosion works but equipment needed and deep holes are a challenge. Acids make untidy holes.

Dave

How about some more details of the part, how deep etc are you going?

Tony

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Chris,

Yes, you said you were trying to drill hardened steel, and you gave an indication of drill size ... BUT you didn't tell us [and still haven't told us] whether you are working on the lathe, or the mill, or what.

It's all relevant to people's understanding of the question.

I made my assumption, others have presumably made theirs ...

MichaelG.

If you're going to drill it with a drill of some sorts, I recommend some RTD cutting compound. No idea how it works, but I've seen a chap fail to drill through some turbine blade-grade stainless, then reach into his bag, draw out a tube of RTD and apply it. Using the same drill bit, in the same hole, it went through like it was mild steel.

Spark Erosion Apparatus

Well now we know what it is I would think most of us would suggest the lathe rather than the mill to drill the hole axially in a round object. Had it been a flat clock spring then the mill would be the better option.

I also wonder why you could not drill it with a HSCO drill when we have seen from other posts that pivot steel can be worked with HSS, Maybe something else going on that is giving you problems

You can also buy pivot drills made from carbon steel and HSS, not just carbide. The name generally describes a style with a short small end and then a larger diameter longer shank The cutting end can be flat or spiral flute like a modern twist drill. Example here

Strangely the only pivot drills I can see on Timesavers site are carbon steel and not carbide? Can't even see pivot drills on Eternal's site??

Edited By JasonB on 17/02/2020 20:58:40

Jason, Take another look at the Example here you posted when I look at it it clearly states for brass, mild steel and does not specify for hardened steel.

I have got the answer fto my satisfaction rom many sources now so with all due respect thank you and let's move on.

chris

It's nice to see that Mr. C.T-T finally also has learned how to quote correctly. For such an old git like me it is really cumbersome to find out who has written what. I sincerely hope that from now on, as you wrote, you will move on.

Kind regards,
Hans

Clearly they do not need to supply drills for hardened steel - because it is soft when annealed! Simples. Nor is there a need to harden the piece after fitting the new pivot, either.

For a guy knowing jack all this C T T person sure has attitude in quantity eh? I hope he moves on also.

For what it’s worth [ which in the context of this discussion might be ‘not much’ ] ...

Here is a short video from Eternal Tools, which I have posted before: **LINK**

https://youtu.be/4jTKNLjLrNM

The brief clip starting at about 1m:45s nicely illustrates sharpening of a solid tungsten carbide spade drill.

< That’s All, Folks ! >

MichaelG.

Not at all, everybody welcome! Chris made a few mistakes, that's all.

1. Insufficient description in his original question, leaving the team guessing. No doubt crystal clear to Chris what he meant, the rest of us were left joining a couple of dots.
2. Not understanding that broad questions attract broad answers, and perhaps sharp comment because no one likes having their time wasted.
3. Stubbornly not providing the detail when asked.
4. Not understanding that other people might be irritated by Chris too.
5. Rebutting advice using information from other web-sources without explaining the context. (Again probably clear to Chris but not the rest of us.)
6. Summarising conclusions with enough ambiguity to suggest about 20% of the problem hasn't been understood, and then shutting down the thread.
7. Arguing with Jason! Presumably Chris isn't aware of Jason's extraordinary track-record as practical man, author and first-rate explainer of workshop technique.
8. Having a higher opinion of his level of understanding than seems justified.

Chris isn't the only forum member to accidentally put his foot in it. We all get stuff wrong occasionally. Good grief, I'm the most lovable, intelligent, and sociable bloke on the planet, a saint in waiting, and yet not everyone likes me! Dunno why not, after all I'm handsomer, wittier and brainier than lesser men, and my politics are irrefutable...

Storm in a teacup!

Dave

Hi Dave, I've never made a mistake, since the last one.

Regards Nick.

Highest quality work since Monday afternoon.